Anal sex is a relatively common sexual practice among young heterosexual women and men. Anal sex is also a highly efficient mode of STI acquisition. However, anal sex remains understudied in the sexual and reproductive health and family planning literature. To date there is a dearth of research data examining young heterosexual women’s decision-making around anal sex and its association with sexual and reproductive health. To address this gap, this study will recruit thirty young women (age 15-24 years) who report lifetime experience of anal sex to participate in a qualitative study using in-depth interviews. Interviews will cover topics related to the sexual and reproductive health contexts within which anal sex occurs (e.g. type of partner, length of relationship, contraceptive practices); how young women evaluate and prioritize the risks of STIs vs. pregnancy in relation to anal sex behaviors; whether and how anal sex is used as a form of pregnancy prevention; how anal sex is initiated and by whom; partner power dynamics and anal sex; how women describe their experiences with anal sex; and past discussions about anal sex with a health care provider. By focusing on anal sex specifically among young women, and the interplay between pregnancy and STI prevention, this study will provide valuable information about young women’s decision-making around anal intercourse, providing critical information for sexual and reproductive health providers and researchers on the social context surrounding heterosexual anal sex practices.